KR20040001909A - Method for forming gate electrode of semiconductor device - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to provide a method for forming a gate electrode of a semiconductor device suitable for preventing abnormal oxidation of a tungsten film due to the formation of a buffer oxide film. Stacking an insulating film for a gate insulating film and a first conductive film for a gate electrode, a second conductive film, and an insulating film for a hard mask on the substrate; Forming a photoresist pattern for forming a gate electrode pattern on the hard mask; Etching the photoresist pattern as an etch mask, the hard mask insulating film, the second conductive film, the first conductive film, and the insulating film are sequentially etched to stack a gate insulating film, a first conductive film pattern, a second conductive film pattern, and a hard mask. Forming a gate electrode pattern having a structure; Removing the photoresist pattern; And forming a buffer oxide film along the first conductive film pattern, the second conductive film pattern, and the surface of the substrate through a selective oxidation process using plasma to compensate for etch damage of the gate insulating film. Provided is an electrode forming method.

Description

Method for forming gate electrode of semiconductor device

The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for forming a gate electrode of a semiconductor device.

As a high speed of operation is required for semiconductor devices, a material having higher conductivity is used as an electrode contacting a gate, a drain, or a source.

For example, US Pat. No. 5,814,537 (Method of forming transistor electrodes from directionally depositedsilicide, Jer-shen Maa, etc., 1998/9/29.) Or US Pat. No. 5,194,403 (Method for the making of the electrodemetalization of a transistors, As in Sylvain Delage, etc., 1993/4/16), a material such as silicide or metal is used as a gate or an electrode. In addition, for high speed of operation, US Pat. No. 5,804,499 (Prevention of abnormal WSiX oxidation by in-situ amorphous silicon deposition, Christine Dehm, etc., 1998/9/8.) Uses tungsten silicide (WSix) as a gate. have. It also describes protecting tungsten silicide with amorphous silicon in order to prevent oxidation of tungsten silicide.

In order to form a gate, a process of stacking a gate oxide film and a conductive layer on a semiconductor substrate and then patterning the conductive layer to a required scale is essential. In this patterning process (pattern forming process), the lower gate oxide film is damaged. In particular, such damage may be concentrated in the edge portion of the gate oxide layer, that is, the portion adjacent to the sidewall of the patterned conductive layer. Such damage may cause deterioration of transistor characteristics, and thus involves a process of recovering through heat treatment or the like.

1A to 1D are cross-sectional views illustrating a gate electrode forming process of a semiconductor device according to the related art, which will be described later in detail.

First, as shown in FIG. 1A, the polysilicon film 12a and the tungsten film 13a are formed on the substrate 10 on which various elements for forming a semiconductor device are formed, as the conductive film of the gate insulating film 11a and the gate electrode. Next, the nitride film 14a for the gate electrode hard mask is sequentially stacked, and the photoresist pattern 15 for forming the gate electrode pattern is formed on the nitride film 14a.

Subsequently, as shown in FIG. 1B, the nitride film 14a, the tungsten film 13a, the polysilicon film 12a, and the oxide film 11a are sequentially etched by a selective etching process using the photoresist pattern 15 as an etching mask. A gate electrode pattern having a structure in which the gate insulating film 11b, the polysilicon film 12b, the tungsten film 13b, and the conductive film for the gate electrode and the hard mask 14b are stacked is formed. Subsequently, the photoresist pattern 15 is removed.

On the other hand, the etching process for forming the pattern is a dry etching using a plasma, at this time, the lower gate insulating film 11b is also eroded and damaged by the dry etching method.

Although not shown in the drawings, a predetermined amount of polymer is generated during the etching of the tungsten film 13a and the polysilicon film 12a and remains on the surface of the photoresist and the etched polysilicon film 12b and the tungsten film 13b. Done.

Thus, a thin hydrofluoric acid solution is used to wet remove the polymer (not shown).

Meanwhile, as shown in FIG. 1C, in order to recover the damage of the gate insulating film 11b described above, when the heat treatment in an oxidizing atmosphere is performed, the sidewall surface of the polysilicon film 12b is oxidized to form the buffer oxide film 16. As a result, damage to the damaged gate insulating film 11b, in particular, damage to the edge portion in contact with the sidewall of the patterned polysilicon film 12b is recovered.

The above-mentioned heat treatment in an oxidizing atmosphere is a conventional selective oxidation process. In the hard mask 14b mainly using a nitride film, the silicon-containing polysilicon film 12b and tungsten are used in that the oxidation does not occur due to the characteristics of the nitride film. It is formed by heat treatment to selectively generate oxidation only in the film 13b, and serves to improve the refresh characteristics of the semiconductor device by relieving stress between the spacer of the subsequent nitride film series and the substrate 10.

1D is a thin spacer 17 such as a nitride film formed along the profile in which the gate electrode pattern is formed as described above.

The spacer 17 has an etch selectivity with an oxide film, which is an interlayer insulating film, in a subsequent self-aligned contact (SAC) process, so as to obtain an SAC etch profile, and to reduce the loss of the hard mask 14b. To prevent form.

On the other hand, there is a problem that abnormal oxidation 18 of the tungsten film is likely to occur at a temperature of 500 ° C. or higher when the above-mentioned buffer oxide film is formed.

The present invention proposed to solve the problems of the prior art as described above, an object of the present invention is to provide a method for forming a gate electrode of a semiconductor device suitable for preventing abnormal oxidation of the tungsten film according to the buffer oxide film formation.

1A to 1D are cross-sectional views showing a gate electrode forming process according to the prior art.

2A to 2D are cross-sectional views illustrating a gate electrode forming process according to the present invention.

* Explanation of symbols for the main parts of the drawings

20: substrate 21b: gate insulating film

22b: first conductive film pattern 23b: second conductive film pattern

24b: hard mask 26: buffer oxide film

27: spacer

In order to solve the above problems, the present invention comprises the steps of: laminating an insulating film for a gate insulating film, a first conductive film for a gate electrode containing silicon and a second conductive film and an insulating film for a hard mask on a substrate containing silicon; Forming a photoresist pattern for forming a gate electrode pattern on the hard mask; Etching the photoresist pattern as an etch mask, the hard mask insulating film, the second conductive film, the first conductive film, and the insulating film are sequentially etched to stack a gate insulating film, a first conductive film pattern, a second conductive film pattern, and a hard mask. Forming a gate electrode pattern having a structure; Removing the photoresist pattern; And forming a buffer oxide film along the first conductive film pattern, the second conductive film pattern, and the surface of the substrate through a selective oxidation process using plasma to compensate for etch damage of the gate insulating film. Provided is an electrode forming method.

According to the present invention, after a gate electrode patterning in which a conductive film such as tungsten and polysilicon are laminated, plasma is used in a buffer oxide film forming process to compensate for damage of the gate insulating film by etching and to relieve stress from the substrate with the nitride spacer. The low temperature process is used to prevent abnormal oxidation of the conductive film such as tungsten.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to more easily implement the present invention.

2A to 2D are cross-sectional views illustrating a gate electrode forming process of a semiconductor device according to an embodiment of the present invention.

2A to 2D are cross-sectional views illustrating a gate electrode forming process of a semiconductor device according to the present invention, which will be described later in detail.

First, as shown in FIG. 2A, the polysilicon film 22a and the tungsten film 23a are formed on the substrate 20 on which various elements for forming a semiconductor device are formed, as the conductive film of the gate insulating film 21a and the gate electrode. Next, the nitride film 24a for the gate electrode hard mask is sequentially stacked, and then the photoresist pattern 25 for forming the gate electrode pattern is formed on the nitride film 24a.

Subsequently, as shown in FIG. 2B, the nitride film 24a, the tungsten film 23a, the polysilicon film 22a, and the gate insulating film 21a are sequentially etched by a selective etching process using the photoresist pattern 25 as an etching mask. As a result, a gate electrode pattern having a structure in which the gate electrode conductive film in which the gate insulating film 21b, the polysilicon film 22b and the tungsten film 23b are stacked, and the hard mask 24b are stacked is formed. Subsequently, the photoresist pattern 25 is removed.

On the other hand, the etching process for forming the pattern is a dry etching using a plasma, at this time, the lower gate insulating film 21b is also eroded and damaged by the dry etching method.

Although not shown in the drawings, a predetermined amount of polymer is generated when the tungsten film 23a and the polysilicon film 22a are etched to remain on the surface of the photoresist and the etched polysilicon film 22b and the tungsten film 23b. Done.

Thus, a thin hydrofluoric acid solution is used to wet remove the polymer (not shown).

Meanwhile, to recover the damage of the gate insulating film 21b described above, as shown in FIG. 2C, the sidewall surface of the tungsten film 23b and the substrate 20 of the polysilicon film 22b are subjected to a selective oxidation process using plasma. This oxidation causes a buffer oxide film 26 to be formed. As a result, damage to the damaged gate insulating film 21b, in particular, damage to the edge portion in contact with the sidewall of the patterned polysilicon film 22b is recovered.

In the selective oxidation process, the present invention is carried out under a pressure of 10 mTorr to 1 Torr and a temperature of 200 ° C to 400 ° C, thereby preventing abnormal oxidation that has occurred in the tungsten film 23b by a process performed at a conventional temperature of 500 ° C or more. Can be.

At this time, and it includes only the O ₂ gas or a plasma of the O ₂ gas containing the inert gas, or silane (SiH ₄₎ gas, such as He, Ne, Ar or Xe, microwave (Microwave), ECR (Electron Cyclotron Resonance) Or equipment using a method such as inductive coupled plasma (ICP) is used.

On the other hand, dry cleaning may be used instead of wet cleaning using the above-described diluted hydrofluoric acid solution. In this case, after transferring to microwave, ECR or ICP equipment to form the buffer oxide film 26, O ₂ and fluorine (F) -based After washing with a plasma containing gas, a buffer oxide film 26 is formed by an in-situ process.

The selective oxidation process described above is selectively performed only on the polysilicon film 22b, tungsten film 23b, and the substrate 20 containing silicon, by which the oxidation does not occur in the hard mask 24b mainly using the nitride film. The oxidation of the buffer layer 26 is performed to form a buffer oxide layer 26. The buffer oxide layer 26 serves to improve the refresh characteristics of the semiconductor device by relieving physical stress caused by the difference in thermal expansion between the spacer of the nitride layer series and the substrate 20. FIG.

2D is a thin spacer 27 such as a nitride film formed along the profile in which the gate electrode pattern is formed as described above.

The spacer 27 may have an etching selectivity with an oxide film, which is an interlayer insulating film, in a subsequent SAC process to obtain an SAC etching profile, and to prevent loss of the hard mask 24b.

The present invention made as described above. A buffer oxide film is formed between the substrate and the spacer to relieve stress to improve leakage current characteristics, and to reduce the etching damage of the gate insulating film due to the formation of the gate electrode pattern through the buffer oxide film, thereby forming a buffer oxide film through a low temperature process. It can be seen through the examples that it is possible to prevent abnormal oxidation of tungsten.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The present invention described above can prevent abnormal oxidation of the tungsten film used as the gate electrode when forming the buffer oxide film formed to improve the gate insulation film etching compensation and refresh characteristics, and ultimately improve the yield and characteristics of the semiconductor device. You can expect an excellent effect.

Claims (8)

Stacking an insulating film for a gate insulating film, a first conductive film for a gate electrode containing silicon, a second conductive film and an insulating film for a hard mask on a substrate containing silicon; Forming a photoresist pattern for forming a gate electrode pattern on the hard mask; Etching the photoresist pattern as an etch mask, the hard mask insulating film, the second conductive film, the first conductive film, and the insulating film are sequentially etched to stack a gate insulating film, a first conductive film pattern, a second conductive film pattern, and a hard mask. Forming a gate electrode pattern having a structure; Removing the photoresist pattern; And Forming a buffer oxide film along the first conductive film pattern, the second conductive film pattern, and the substrate surface through a selective oxidation process using plasma to compensate for the etching damage of the gate insulating film; Gate electrode forming method of a semiconductor device comprising a. The method of claim 1, Forming the buffer oxide film, A method of forming a gate electrode of a semiconductor device, characterized in that carried out under a pressure of 10mTorr to 1Torr and a temperature of 200 ℃ to 400 ℃. The method of claim 2, Forming the buffer oxide film, Including only the O ₂ gas or a plasma comprising an inert gas or a silane gas to O ₂ gas microwave, ECR, or the gate electrode forming method of a semiconductor device, characterized in that for performing the equipment using any of the methods of the ICP. The method of claim 1, And removing the photoresist pattern, followed by cleaning to remove residues due to the etching. The method of claim 4, wherein The method of forming a gate electrode of a semiconductor device, characterized in that to use a dilute hydrofluoric acid solution in the cleaning step. The method of claim 4, wherein In the cleaning step using a plasma of O ₂ and F-based gas, at this time, the step of forming the buffer oxide film in the equipment using any one method of microwave, ECR or ICP and in-situ A method of forming a gate electrode of a semiconductor device. The method of claim 1, The first conductive film is a method of forming a gate electrode of a semiconductor device, characterized in that it comprises polysilicon. The method of claim 1, The second conductive film is a gate electrode forming method of a semiconductor device characterized in that it comprises tungsten.